Electrode assembly



DCC 19,1967 H|TosH| TSUYAMA ETAL 3,359,447

ELECTRODE ASSEMBLY Filed May 20, 1964 M45-hm Q M4541 m United States Patent O 3,359,447 ELECTRODE ASSEMBLY Hitoshi Tsuyama and Hiroshi Hirose, Kokubunji-machi, and Junichi Okamoto, Meguro-ku, Tokyo-to, Japan, assignors to Kabushiki Kaisha Hitachi Seisakusho, Chiyoda-ku, Tokyo-to, Japan, a joint-stock company of Japan Filed May 20, 1964, Ser. No. 368,952 Claims priority, application Japan, May 28, 1963, 38/ 38,433 2 Claims. (Cl. 313-250) This invention relates to improvements relating to an electrode assembly comprising a plurality ofV electrodes.

It is required to assemble with high accuracy a plurality of electrodes in devices such as an ion source of a mass spectrometer or an electron gun of an accelerator for electrically charged particles. Generally, this plurality of electrodes must be maintained in spaced relations and insulated from each other, and for this purpose electrical insulators are interposed between adjacent electrodes. Usually, the accuracy of said assembly is principally dependent upon the accuracy of fabrication of the insulators and their assembled construction. Thus it will be easily understood by those skilled in the art that it is preferable to simplify as much as possible the finished shape of said insulators in order to improve their accuracy of fabrication or machining and also to simplify their assembled construction to minimize the error introduced during assembly.

Accordingly, the principal `object of this invention is to provide an improved electrode assembly utilizing insulators which can be prepared with high accuracy and can be assembled without error of assembly.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention will be better understood from the following description taken in connection with the accompanying drawing, in which:

FIG. 1 shows a top plan view of an electrode assembly according to prior art;

FIG. 2 is a cross sectional view taken along line X-X' in FIG. 1;

FIG. 3 illustrates one embodiment showing a top plan view of an electrode assembly constructed in accordance with the principle of this invention;

FIG. 4 shows a cross sectional view of the electrode assembly taken along line Y-Y' in FIG. 3; and

FIG. 5 shows a cross sectional view taken along line X-X' in FIG. 3.

Referring now to FIGS. 1 and 2, there is illustrated one example of the prior art electrode assembly of the type referred to above comprising electrodes 1, 2, 3, and 3', the electrodes 3 and 3' being half plates or semicircular plates positioned to define therebetween a slit 8 of a width S. As shown in FIG. 2 these electrodes are superposed one upon the other with ring-shaped insulating spacers 4 and 5 interposed between them, and clamped together to form a unitary assembly by means of a number of bolts 9, 9', 9", and 9". The top and bottom electrodes 6 and 7 are provided with openings 7 at their central portion to pass charged particles. Although electrodes 1, 2, 3, and 3' are maintained parallel to each other by insulating annular spacers 4 and 5, since they have such configuration as to permit slight lateral and rotational movements of the electrodes, it is difficult to accurately align the openings 6 and 7 serving to pass charged particles and the slit 8 and to maintain the electrodes in parallel relationship. In addition, as the insulating spacers are in the form of annular rings, gaps between adjacent electrodes are substantially sealed off except for small open- 3,359,447 Patented Dec. 19, 1967 lCC ings 6 and 7 comprising the passage for charged particles and the slit 8. As a consequence, it is impossible to see the interior of theelectrode assembly,I from the outside. Further, this construction results in lowering of the vacuum within these gaps, thereby scattering the charged particles.

This invention contemplates completely obviating the various disadvantages just mentioned, and in accordance with this invention, insulating spacers to be interposed between adjacent electrodes are made as linear bars or plates having square or rectangular cross sections. These spacers are positioned in parallel grooves provided in the opposing surfaces of the adjacent electrodes with a portion of each of the spacers embedded in the corresponding grooves, thereby to accurately determine the position of the respective openings` for passing charged particles.

Referring now to FIGS. 3-5 of the accompanying drawing illustrating one preferred form of the electrode assembly of this invention, there are shown four electrodes 11, 12, 13, and 13', of which electrodes 13 and 13' are half plates adapted to define a slit 18 between them. These electrodes are superposed one upon the other with insulator spacings 14, 14', 14" and 14"' in the form of square bars interposed between them. The upper and lower portions of these spacers are received in grooves 15, 15', 15", and 15"' provided in the respective electrodes. Like the electrode assembly shown in FIG. 1, the assembly shown in FIGS. 3-5 is clamped by means of bolts 19, 19', 19", and 19". As is best shown in FIG. 5 the upper and lower electrodes 11 and 12 are provided, at their centers, with openings 16 and 17 for passing charged particles. Thus, in the electrode assembly of this invention, the respective electrodes 11, 12, 13, and 13 are provided with parallel grooves 15, 15', 15", and 15"' to slidably receive insulating spacers 14, 14', 14, and 14" in the form of square bars, land these insulating spacers are partly embedded in the corresponding grooves, thereby affording accurate alignment of the openings 16 and 17 for passing charged particles with the slits between the half plates 13 and 13 and also maintaining these electrodes in parallel. Thus, by slidably embedding the insulating spacers in the electrodes in the transverse direction thereof, relative movements of the electrodes in a direction normal to said grooves and rotational movements of the electrodes during assembly can be positively prevented, thereby affording simpliiicaiton of assembly procedure as well as improvement in the accuracy of assembly with the added advantage of accurate positioning of openings for passing charged particles. Moreover, as the novel insulating spacers do not close the gap between electrodes, it is possible to satisfactorily evacuate the gap, thereby preventing charged particles from scattering. Alternatively, parallel insulating spacers can be disposed at right angles to the slit 18 to adjust the width S thereof to any desired value.

While the invention has been explained by describing a particular embodiment thereof, it will be apparent that improvements and modifications may be made therein without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. An electrode assembly comprising a plurality of praallel-spaced planar electrodes, each having at the center thereof a thin elongated rectangular opening for passing charged particles, and at least a pair of mutually parallel, straight guide grooves extending perpendicularly to the longitudinal axis of said rectangular openings provided in the surface of said respective electrodes which confronts the surface of adjacent electrodes; and at least a pair of long insulating spacers of rectangular columnar shape disposed in parallel between the adjacent electrodes and extending in the direction perpendicular to the longitudinal axis of said thin elongated rectangular openings, said respective insulating spacers being slidably embedded in said guide grooves provided in the opposing surfaces of said adjacent electrodes, whereby said plurality of electrodes are constructed to be mutually parallel, the longitudinal axis of said thin elongated rectangular openings are made parallel one after the other, and said respective electrodes are permitted relative transverse movement in the direction perpendicular to the longitudinal axis of said openings, relative transverse and rotational movements in other directions thereof being prevented.

2. An electrode assembly comprising two equal, parallel-spaced planar electrodes having thin elongated rectangular openings for passing charged particles at the respective center thereof; a pair of half plates, together of subsantially equal size to said electrodes, disposed therebetween; and four straight insulating spacers of columnar shape to insulatively separate and support said electrodes and half plates, said openings provided in said both electrodes and a slit formed by said pair of half plates being aligned in the direction parallel to their respective longitudinal axes, the opposing surfaces of said respective electrodes and half plates being provided with four guide grooves which are mutually parallel in the direction perpendicular to the longitudinal axes of said openings and in which said four insulating spacers are slidably em- -bedded, whereby relative, transverse and rotational movements in the longitudinal axis of said openings of the respective electrodes and the slit formed by said half plates References Cited UNITED STATES PATENTS 1,017,648 2/1912 Greene et al 313-325 X 1,348,350 8/1920 Davis 313-9 2,469,215. 5/1949 Smith 313-268 X 2,581,446 1/1952 Robinson 313-25() 2,782,337 2/1957 Robinson 313--250 2,916,649 12/1959 Levin 313-250 2,918,598 12/1959 Rose 313-292 X 3,176,164 3/1965 Beggs 3 l3-258 X FOREIGN PATENTS 648,421 9/1962 Canada.

OTHER REFERENCES Glass Frit Spacing of Vacuum Tube Element, RCA Technical Notes No. 195, Aug. 18, 1958.

JOHN W. HUCKERT, Primary Examiner.

A. I. JAMES, Assistant Examiner. 

1. AN ELECTRODE ASSEMBLY COMPRISING A PLURALITY OF PARALLEL-SPACED PLANAR ELECTRODES, EACH HAVING AT THE CENTER THEREOF A THIN ELONGATED RECTANGULAR OPENING FOR PASSING CHARGED PARTICLES, AND AT LEAST A PAIR OF MUTUALLY PARALLEL, STRAIGHT GUIDE GROOVES EXTENDING PERPENDICULARLY TO THE LONGITUDINAL AXIS OF SAID RECTANGULAR OPENINGS PROVIDED IN THE SURFACE OF SAID RESPECTIVE ELECTRODES WHICH CONFRONTS THE SURFACE OF ADJACENT ELECTRODES; AND AT LEAST A PAIR OF LONG INSULATING SPACERS OF RECTANGULAR COLUMNAR SHAPE DISPOSED IN PARALLEL BETWEEN THE ADJACENT ELECTRODES AND EXTENDING IN THE DIRECTION PERPENDICULAR TO THE LONGITUDINAL AXIS OF SAID THIN ELONGATED RECTANGULAR OPENINGS, SAID RESPECTIVE INSULATING SPACERS BEING SLIDABLY EMBEDDED IN SAID GUIDE GROOVES PROVIDED IN THE OPPOSING SURFACES OF SAID ADJACENT ELECTRODES, WHEREBY SAID PLURALITY OF ELECTRODES ARE CONSTRUCTED TO BE MUTUALLY PARALLEL, THE 